SQL GROUP BY and HAVING for Business Reports

Understanding GROUP BY

GROUP BY groups rows that have the same values in specified columns. It is often used with aggregate functions like COUNT, SUM, AVG, MIN, and MAX.

This clause helps summarize data, such as total sales per region or number of customers per product.

• Syntax: SELECT columns, aggregate_function(column) FROM table GROUP BY columns;
• Groups rows sharing the same values in the GROUP BY columns.
• Aggregate functions compute summary values per group.

Filtering Groups with HAVING

HAVING filters groups created by GROUP BY based on aggregate conditions. It is similar to WHERE but applies after grouping.

Use HAVING to include only groups meeting criteria, such as regions with sales above a threshold.

• Syntax: SELECT columns, aggregate_function(column) FROM table GROUP BY columns HAVING condition;
• HAVING conditions often use aggregate functions.
• Filters groups, not individual rows.

Practical Business Reporting Examples

Combining GROUP BY and HAVING enables detailed business reports, such as:

- Customer segments with average purchase above a certain amount.

- Products with sales counts exceeding a target.

- Monthly revenue grouped by product category, filtered by minimum revenue.